Heat exchangers of the above type serve, as a rule, for transferring the heat contained in a fluid steam medium to a fluid cooling medium. The steam medium thereby cools, while the cooling medium heats up. If appropriate, the heat exchanger is designed such that the cooling of the steam medium leads to a condensation of the steam medium, in this case a heat exchanger also being designated as a condenser, in particular steam condenser. Heat exchangers, in particular condensers of the type mentioned, are conventionally installed in power plants. There, a fluid steam medium serves, as a rule, as a working medium for driving a turbine and in this case discharges its kinetic energy for driving the turbine to a turbine rotor which, in turn, serves for driving a generator.
Accordingly, a steam medium located on the turbine outlet side is, as a rule, in an expanded state, that is to say it has a pressure in the region of 1 bar and is hardly superheated. This steam medium located on the turbine outlet side is, as a rule, supplied to a heat exchanger, in particular a condenser of the abovementioned type. The aim, as a rule, is to condense the steam medium, if appropriate also further to utilize its heat content after discharge to the cooling medium.
Conventionally, the boundary of a steam medium routing in a heat exchanger of the above type is formed by a walling which is constructed from a multiplicity of heat exchanger tubes of the cooling medium routing. Other concepts provide cooling medium routings arranged transversely in a steam medium routing, so that a steam medium routed in the steam routing has to flow past the multiplicity of heat exchanger tubes of the cooling medium routing. In this case, the closed-in volume of such heat exchangers, in particular of steam condensers, should, depending on the design, be kept as low as possible and be optimized such that the efficiency of such heat exchangers is as high as possible. The aim in a heat exchanger is therefore to configure the heat transfer in a heat exchanger tube as effectively as possible, so that the amount of heat contained in the steam medium can be supplied as fully as possible to the cooling medium and is not otherwise lost or does not remain undesirably in the steam medium. An obstruction of the heat transfer occurs, for example, due to a formation of an insulating condensation film on an outside of a heat exchanger tube. An obstruction of the heat transfer is the more serious, the denser an insulating condensation film of this type is on an outer surface of a heat exchanger tube. In this case, the nature of such a condensation film depends critically on the drop formation or on the dripping behavior of condensed steam medium.
A further impairment of the heat transfer occurs due to the encrustation on the cooling medium side on an inside of a heat exchanger tube. Such encrustation occurs over time, in that inorganic and organic constituents contained in the cooling medium settle and accumulate on the inner surface of a heat exchanger tube. Although various cleaning measures can greatly slow this effect down, they are complicated and cannot prevent the process as such.
A heat exchanger tube and a use relating to the heat exchanger tube, which provide improved heat transfer, would be desirable. It would also be desirable to have a heat exchanger with improved efficiency which is not impaired unnecessarily due to poorer heat transfer in a heat exchanger tube.